In general, if hydrogen and oxygen are unevenly distributed in a fuel electrode of a fuel cell when the fuel cell is started, a local potential is generated in a region where a hydrogen concentration is relatively high and serves to cause a current flow in a direction opposite to that in a normal power-generating state in a region where an oxygen concentration is relatively high. Therefore, an oxidizer electrode, in particular, quickly deteriorates. In order to solve this problem, an invention for discharging oxygen that remains in the fuel electrode and replacing the oxygen with hydrogen gas in a short time is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2004-139984 (see page 12 and FIG. 14). According to this invention, when a fuel cell is started, a control value of a secondary pressure regulator is set to be higher than a supply pressure in a normal power-generating state and hydrogen is supplied to the fuel cell by opening a hydrogen supply solenoid valve while driving a hydrogen pump.